Slide key switch with improved plunger actuating mechanism with lost motion coupling

ABSTRACT

A slide key switch unit contained within a housing having a front opening with an extending portion, extending beyond the front opening of the housing. A plurality of electrical contacts are formed in the housing and a helical adjusting spring is disposed in the extending portion and urged against a key actuating plunger which is also slidably disposed in the front opening of the housing and engaging the extending portion.

United States Patent Schadow June 27, 1972 [54] SLIDE KEY SWITCH WITH IMPROVED PLUNGER ACTUATING MECHANISM WITH LOST MOTION COUPLING [72] lnventor: Rudolf Sci-dew, Konigsbacher Zeile 23,

[000 Berlin 28, Germany [22] Filed: Dec. 18, I970 [21] Appl. No.: 99,377

[30] Foreign Application Priority Data May 6, 1970 Germany ..P 20 23 109.8

[52] 05. CL ll, 200/16 D, 200/17 R, 200/153 V [51] int. Cl. ..ll01l| 15/14 [58] Field oiSearch............200/5 R,5 A, 16 F, 168, 169 PB, 200168, 16 R, 16 D, 16 F, 17 R, 153 V [56] References Cited UNITED STATES PATENTS 2,156,946 5/1939 Closson et 11 ..200/169 PB 2,902,550 9/1959 Allison ..200/i6 F 2,633,510 3/1953 Schellrnan 3,312,809 4/1967 Hill e! :1 ..200/|69 PB 3,457,377 7/1969 Olson ..200/5 R 3,258,549 6/1966 Stoi ..200/17 R X Primary Examiner-J. R. Scott Attorney-Allison C. Collard ABSTRACT A slide key switch unit contained within a housing having a front opening with on extending portion, extending beyond the front opening of the housing. A plurality of electrical contacts are formed in the housing and a helical adjusting spring is disposed in the extending portion and urged against a key actuating plunger which is also slidably disposed in the front opening of the housing and engaging the extending portion.

10 Claims, 5 Drawing Figures minimum?1:72 3.673.365

SHEET 2 OF 2 Attorney SLIDE KEY SWITCH WITH IMPROVED PLUNGER ACTUATING MECHANISM WI'III DOST MOTION COUPLING This invention relates to a sliding key switch unit having a closed plastic housing with only a front opening for receiving a plastic key actuating plunger. A spiral like readjusting spring engages the key actuating plunger.

These switch units may be used individually, or can be assembled as key switch aggregates or groups, and are used primarily for radio, electrical communication, control circuits, and electronic technology.

The present invention provides a switch which is suitable for a large amount of switching. For this purpose, a relatively long spiral-like adjustment spring is mounted in a space saving manner in the switch housing. It should be noted that the mounting of the readjustment spring is bend free within the housing. Furthermore, an improved guide for the key plunger and the key button is provided by an improved housing design.

For convenu'onal switches of this type, the spiral like readjustment spring is either mounted around the outer face of a shaft of the key plunger, or is mounted in a hollow space of the key plunger between a trunnion of the key housing and a trunnion in the hollow space of the key slider so that these trunnions form counter bearings. In contrast to these conventional switches, the inventive switch provides a readjustment spring which is inserted into the front opening of the housing, so that it is completely covered, on the one hand by the actuating plunger, and by a housing extension which extends to the key button on the other hand. Another advantage is obtained with this arrangement in that the readjustment spring is guided absolutely concentrically on the outside, but not on the inside. Even for small diameters and long lengths, the spring can be mounted on the inside of the housing. In the inventive switch, the actuating plunger together with the contact slider can be pulled out at the front, after a cross bar is removed from the housing. The readjustment spring is also automatically centered when it is inserted in the switch housing.

In accordance with a further embodiment of the invention, there are two defined switching positions of the contact slide which carries the contact bridges. The bridges are not rigidly connected with the key plunger, but are elastically connected by means of a pressure spring, or are dragged without a spring. The contact slide is pushed against an abutment in its end position, by means of the pressure spring or coupling spring, while the key plunger may be moved a few more millimeters, in order to actuate further catches or stops independently from each other. If no pressure spring or coupling spring is provided, the key plunger may be moved a few millimeters to release ratchets before the contact slide can be moved.

It is, therefore, an object according to the present invention to provide a sliding key switch suitable for a large number of operations using a key actuating plunger.

It is another object according to the present invention to provide a sliding key switch which is simple in design, easy to manufacture and reliable in operation.

Other objects and features of the present invention will become apparent from the following detailed description considered in connection with the accompanying drawings which more clearly define the embodiments of the invention. It is to be understood, however, that the drawings are designed for the purpose of illustration only and not as a definition of the limits of the invention.

In the drawings, wherein similar reference characters denote similar elements throughout the several views:

FIG. I is a side view of the slide key switch unit according to the invention, whereby the housing and the key button are shown in a cross-sectional view, and the key plunger with the contact slide are shown in a partial cross-sectional view;

FIG. 2 is an exploded view of the key slide unit;

FIG. 3 shows the coupling between the key plunger and the contact slide in a plan view;

FIG. 4 shows a cross-sectional view of the slide key switch unit; and,

FIG. 5 shows a group of key units consisting of a plurality of individual units in a plan view.

Referring to FIGS. 1 and 2, a plastic housing I is provided having a back wall 2, a cover plate 3 and fixed contacts 4 which extend outwardly only at side 4, or at both sides 4 and 4. The housing which carries the fixed contacts is open at the front, while the bottom is extended by a tongue 9, as can be seen in detail in FIG. 2. A tunnel or channel 10 is formed in tongue 9 which receives a spiral-like adjustment spring 12. The adjustment spring is supported by back wall 13 and bridge 14 of tunnel 10. The radius adjustment spring [2, which extends beyond tunnel I0, is covered by tunnel 11, provided in a longitudinally movable key plunger 7. The other support for the adjustment spring is at backwall 15 of the tunnel, and at bridge 16. In this manner, a contact slide 5 can be coupled with key plunger 7 in two different ways, either with a coupling spring 28 or without one. When using a coupling spring 28, contact slide 5 is provided with an extension, consisting of a reduced carrier bridge 25, an enlarged carrier head 26 and a spring trunnion 27, as can be seen in FIGS. 3, 4, and 5. Contact slide 5 is provided with yielding contact bridges 6. The key plunger is provided at its upper part with an open hollow space 29 for carrier head 26 of the contact slide 5, and a reduction 30 for carrier bridge 25. Tninnion 27 is provided for receiving and centering the spiral-like coupling spring 28. The spring is mounted in a hollow space 29, and is supported at one side at carrier head 26, and at backwall 31 of the hollow space 29 at its other end. Carrier bridge 25, spring trunnion 27 and the depth of hollow space 29 are so arranged that a predetermined idle travel of key plunger 7 of x millimeters is obtained. The maximum key stroke of key 8 is defined as the electrical switching of the contact slide stroke y, and the idle movement x of key plunger 7, as can be seen in FIG. 5.

If coupling spring 28 is not provided, key plunger 7 may travel path x without changing the starting position of contact slide 5, and its associated contact bridges 6, with respect to fixed contacts 4. Therefore, idle travel path x is suited for the mechanical actuation of ratchet catches, slides and ratchet: which may have to be actuated before a contact switching can take place.

In a further embodiment of the invention, the safety of the device can be increased in that a yielding catch or stop of the contact slide provides two defined switching positions. For example, ratchet indentations 32 are engaged by a leaf spring 33, or any other suitable means, to provide defined switching positions for the contact slide.

A completely different operation can be achieved with coupling spring 28 in FIGS. 4 and 5 with keys A and C in that plunger 7 can move contact slide 5 in free slide movement by contact stroke y, and therefore move contact slide 5 into a second position defined either by back wall 2 or ratchet combination 32 and 33. Coupling spring 28 can compensate the necessary overstroke of key plunger 7 required for the mechanical arresting or releasing, without changing the defined contact position of contact slide 5. The overstroke corresponds to path .1: according to FIGS. 4 and 5.

The aforementioned coupling operations of key plunger 7 with contact slide 5 by means of a coupling spring 28, or without such a spring can also be achieved by means other than the enclosed adjustment spring 28, namely, by means of an adjustment spring which is only partly covered. A different operation may be necessary when different types of slide key switches are used.

In FIGS. 1 and 2, housing 1 is covered by a cover plate 3 which is penetrated by openings 21, so that a two-footed abutment bolt 19 can be inserted in openings 21. When assembling the switch housing with the associated fixed contacts together with the key plunger and the contact slide, according to FIG. 2, adjustment spring 12 is inserted into tunnel 10 of housing extension 9. Contact slide 5 engages the bottom of the housing. The contact slide is provided with a guide groove 24 and bridge [7. Key plunger 7 is inserted by pressing spring I! together until abutment bolt 19 can be slided with its feet 2] through the cover plates and housing openings 2]. Abutment: 22 define the key rest podtion, as can be seen in FIG. 1.

Key plunger 7 may be provided with lateral walls 23 which would enclose housing tongue 9. Thus, edges 23' may serve as abutrnents, which engage the front face of the housing entrance. in order to limit the maximum stroke of the key. The ratchet mechanism is not shown, because it is old and very well known, and is of no importance to the embodiment of the invention. The same is true for the arrangement of key units in an assembly chassis.

While only a few embodiments of the present invention have been shown and described, it will be obvious that many changes and modifications may be made thereunto without departing from the spirit and scope of the invention.

lclaim:

l. A slide key switch unit, comprising:

a housing, having a front opening and an extending portion extending beyond said from opening;

a plurality of electrical contacts formed in said housing;

a helical adjusting spring disposed on said extending portion in said housing;

a contact slide, having a plurality of yieldable contacts for engagement with said contacts in said housing; and

a key actuating plunger, slidably disposed in the front opening of said housing and engaging said extending portion and said adjusting spring, and including a longitudinal slot having an end opening provided therein, a carrier having an enlarged flange disposed in said actuating plunger slot and coupled to said contact slide, and a coupling spring disposed in said actuating plunger slot for pressing said carrier flange against the opening in said slot.

2. The slide key switch unit as recited in claim 1, comprising a first longitudinal channel formed in said actuating plunger, a second oppositely disposed longitudinal channel formed in said housing and said extending portion, said adjusting spring being disposed in the opening formed by said first and second channels.

3. The slide key switch unit as recited in claim 2 wherein said first and second channels have a cross-sectional profile corresponding to the diameter of said adjusting spring.

4. The slide key switch unit as recited in claim 2 comprising a first support disposed in said housing at one end of said channels for engaging one end oi said adjusting spring and a second support disposed at the other end of said channels in said actuating plunger for engagement with the opposite end of said adjusting spring.

5. The slide key switch unit as recited in claim 4, wherein said first and second supports include key extensions projecting in an opposite direction from said adjusting spring so as to serve as slidable guides for said contact slide and said actuating plunger.

6. The slide key switch unit as recited in claim 5, wherein said housing extension is formed like a tongue and said actuating plunger includes a plurality of sidewalls enclosing said tongue.

7. The slide key switch unit as recited in claim 6, wherein said actuating plunger sidewalls include shoulders formed on their front faces to serve as an abutment to limit the stroke of said actuating plunger.

8. The slide key switch unit as recited in claim 7, wherein said contact slide includes a keyway for slidably engaging the key of said first support in said housing.

9. The slide key switch unit as recited in claim 7, wherein said housing includes a cover plate having a plurality of openings, and wherein said actuating plunger includes a pair of abutment flanges on one end, and a two-footed abutment bar disposed through said cover plate openings and engaging the abutment flanges of said actuating plunger so as to define the rest position of said actuating plunger.

10. The slide key switch unit as recited in claim 9, wherein said contact slide additionally comprises a yieldable ratchet for defining two diflerent switching positions. 

1. A slide key switch unit, comprising: a housing, having a front opening and an extending portion extending beyond said front opening; a plurality of electrical contacts formed in said housing; a helical adjusting spring disposed on said extending portion in said housing; a contact slide, having a plurality of yieldable contacts for engagement with said contacts in said housing; and a key actuating plunger, slidably disposed in the front opening of said housing and engaging said extending portion and said adjusting spring, and including a longitudinal slot having an end opening provided therein, a carrier having an enlarged flange disposed in said actuating plunger slot and coupled to said contact slide, and a coupling spring disposed in said actuating plunger slot for pressing said carrier flange against the opening in said slot.
 2. The slide key switch unit as recited in claim 1, comprising a first longitudinal channel formed in said actuating plunger, a second oppositely disposed longitudinal channel formed in said housing and said extending portion, said adjusting spring being disposed in the opening formed by said first and second channels.
 3. The slide key switch unit as recited in claim 2 wherein said first and second channels have a cross-sectional profile corresponding to the diameter of said adjusting spring.
 4. The slide key switch unit as recited in claim 2 comprising a first support disposed in said housing at one end of said channels for engaging one end of said adjusting spring and a second support disposed at the other end of said channels in said actUating plunger for engagement with the opposite end of said adjusting spring.
 5. The slide key switch unit as recited in claim 4, wherein said first and second supports include key extensions projecting in an opposite direction from said adjusting spring so as to serve as slidable guides for said contact slide and said actuating plunger.
 6. The slide key switch unit as recited in claim 5, wherein said housing extension is formed like a tongue and said actuating plunger includes a plurality of sidewalls enclosing said tongue.
 7. The slide key switch unit as recited in claim 6, wherein said actuating plunger sidewalls include shoulders formed on their front faces to serve as an abutment to limit the stroke of said actuating plunger.
 8. The slide key switch unit as recited in claim 7, wherein said contact slide includes a keyway for slidably engaging the key of said first support in said housing.
 9. The slide key switch unit as recited in claim 7, wherein said housing includes a cover plate having a plurality of openings, and wherein said actuating plunger includes a pair of abutment flanges on one end, and a two-footed abutment bar disposed through said cover plate openings and engaging the abutment flanges of said actuating plunger so as to define the rest position of said actuating plunger.
 10. The slide key switch unit as recited in claim 9, wherein said contact slide additionally comprises a yieldable ratchet for defining two different switching positions. 